Hydrogen photoproduction and carbon dioxide uptake by immobilized Anabaena variabilis in a hollow-fiber photobioreactor

Abstract

Hydrogen (H 2) photoproduction and carbon dioxide (CO 2) uptake by the cyanobacterium Anabaena variabilis was measured under partial vacuum in batch culture and in a photobioreactor. Increasing CO 2 concentrations in the gas phase led to decreased H 2 photoproduction and increased CO 2 uptake by the cells, which was accompanied by O 2 evolution. A laboratory-scale hollow-fiber photobioreactor was constructed for the production of H 2 and uptake of CO 2 by the immobilized cyanobacteria. A two-phase H 2 production-CO 2 uptake system is suggested as being feasible for practical demonstration. In the CO 2 uptake phase the cyanobacterial cells consume CO 2 at rates up to 150 to 170 ml CO 2 g −1 dry wt h −1 and establish conditions for subsequent H 2 photoproduction. In the H 2 production phase the cyanobacteria evolve H 2 at rates up to 20 ml H 2 g −1 dry wt h −1. The photobioreactor was run continuously for over 1 year.